One embodiment of the invention creates an electronic component with at least one pair of functionally identical electronic sub-components.
Electronic components are today used in many areas. One field of use, for example, is the field of ID tags. The ID tags are normally used in arrangements for identifying or locating people, objects or animals. This is done for a large number of purposes, for example in access control systems, inventory management, materials management, production automation etc.
The arrangements generally include a transponder unit and a base station. The ID tags are normally read without direct contact between the transponder unit and the base station i.e. by means of radio transmission for example. Important criteria for specifying such an ID tag are, for example, the operating range i.e. the distance range within which the ID tag can be read, and the dependence on the read position i.e. how exactly the ID tag must be directed towards the base station (read device). Additional criteria for the ID tag are a sufficient data storage capacity and the manufacture price. Generally speaking, in order to make ID tags easier to use, the aim is to manufacture ID tags having as large an operating range as possible and as small a dependence on read position as possible. The data storage capacity should be large enough for it to be possible to differentiate between two products within a supermarket, for example, by means of the information stored on the ID tag. For instance, the German EAN 13 code (CCG Germany EAN 13 standard), which employs 52 bits, can be used for this. In addition, one should note that for many applications, for example for the application as individual product identification in supermarkets, the manufacture costs of the ID tags should be as low as possible.
Radio frequency ID (RFID) systems have emerged as the most effective non-contact automatic ID systems to date. In the radio frequency sector, passive RFID tags, as they are known, are mostly used in order to achieve minimum manufacture costs. They have no battery and provide a high degree of flexibility and reliability. In addition, they also need only little or no maintenance at all.
Passive RFID tag systems generally have two parts: a read device also called the reader, and a passive ID tag. The ID tag normally includes an antenna coil as input and/or output in the form of either a wound or a printed antenna coil, and a semiconductor chip having an integrated rectifier circuit and additional front-end elements that may be simple modulation circuits or non-volatile memories for example. The ID tag is supplied with energy by means of a time varying radio frequency wave, which is generated and transmitted by the reader. This radio frequency signal is also called a carrier signal or carrier. When the electromagnetic field passes through the antenna coil, the flux change of the magnetic field through the coil induces an AC voltage in the coil. This AC voltage is rectified and used as the power source for the ID tag. When power transmitted by means of a reader is available in the ID tag, the information stored in the ID tag is transmitted to the reader.
The transmission of the information between the reader and the ID tag is based on the modulation of the electromagnetic field generated by a coil of the reader. By repeated parallel connection of the ID tag coil, i.e. coupling as an inductive load, by means of a transistor, the ID tag can cause slight fluctuations in the electromagnetic field of the carrier wave of the reader. The electromagnetic coupling between ID tag and reader is essentially behaving like a transformer. When the coil of the ID tag, which can be regarded as a secondary winding, is briefly connected in parallel, the coil of the reader, which can be regarded as a primary winding, experiences a brief voltage drop i.e. amplitude modulation of the electromagnetic field transmitted by the reader. This is often referred to as backscatter. By detecting this backscatter signal, the information stored in the ID tag can be received and identified in full in the reader. This amounts to bi-directional communication between the reader and the ID tag.
This amplitude modulation of the electromagnetic field of the reader provides a communication path back to the reader. The data bits, i.e. the data stored in the ID tag and transmitted to the reader, can be encoded in a number of different ways or further modulated.
The electromagnetic field generated by the ID tag reader serves more than one purpose. First, it is used to induce sufficient energy in the coil of the ID tag for the ID tag to be supplied with enough power. Second, it provides a synchronisation clock for the ID tag. Third, the electromagnetic field is used as the carrier wave for transmitting to the reader the information stored in the ID tag.
The typical procedure, known as “handshaking”, for establishing and checking a communication link between an ID tag and a reader is as follows:                The reader generates a continuous sinusoidal radio frequency carrier wave, constantly checking whether this carrier wave is being modulated. Detected modulation of the carrier wave, or in other words of the electromagnetic field, indicates the presence of an ID tag.        An ID tag enters the radio frequency field generated by the reader. As soon as the ID tag has absorbed enough energy to function correctly, it modulates the carrier wave and hence begins to clock to an output transistor, i.e. to transmit synchronously, the data stored in the ID tag. Normally the output transistor switches the antenna coil of the ID tag.        The output transistor of the ID tag connects, depending on the data stored in the ID tag, the antenna coil in parallel, i.e. the antenna coil of the ID tag is coupled inductively to the reader as a load, whereby the data is read synchronously from the memory of the ID tag.        The parallel connection of the antenna coil of the ID tag causes a brief fluctuation (attenuation) of the carrier wave, which can be detected as a slight change in the amplitude of the carrier wave.        The reader detects the amplitude modulated data and processes the resulting bit stream according to the coding and data modulation technique that was used.        
The amplitude modulation of the electromagnetic field of the reader provides a communication path back to the reader. The data bits, i.e. the data stored in the ID tag and transmitted to the reader, can be encoded in a number of different ways or further modulated.
Although all the data is transmitted to the reader by backscatter modulation as described above, the actual modulation of the individual data bits is implemented as a “1” and a “0” by means of the direct modulation technique.
In direct modulation, a “high-level” in the envelope of the carrier wave is evaluated as a “1” and a “low-level” as a “0”. This direct modulation can produce a high data rate, but provides only a low noise immunity.
The state of the art described here, as described in An Ultra Small RF Identification Chip for Individual Recognition Applications, Mitsuo Usami, et al., IEEE International Solid-State Circuits Conference (2003), Session 22.7 for example, has many disadvantages.
For example, the ID tag requires a relatively large surface area, because many electronic components, for example a rectifier circuit, must be arranged on the chip of the ID tag. This rectifier circuit not only requires surface area but also consumes power. This increases costs and degrades the cost/surface-area ratio. It also has complex geometry, one reason for this being a mix of components for different voltage supplies. In addition, this mix also results in power losses in the conversion from AC voltage to DC voltage or vice versa. In addition, the relatively high complexity of the ID tag also makes it impossible for this type of architecture to be implemented on other lower-cost substrates such as polymers.
An interrogator system having a passive label is known from GB 2 165 423 and includes an interrogator for transmitting interrogation signals, one or more labels or passive transponders which produce a reply signal containing coded information in response to the interrogation signal, and a receiver and decoder for receiving and decoding the information contained in it.
A receive/backscatter arrangement for implementing non-contact data transmission is known from US 2003/0102961 and includes an integrated circuit having two antennas, three capacitors connected in series between the two antennas, the center capacitor being a MOS varactor, a controllable, variable voltage source switched via the MOS varactor, and a control unit that controls the voltage source.